“It would be not uncommon for people to say, ‘I’m going to Atlanta; I’m going to Georgia,’” Manjarrez said. “The risk on that is you have no idea who that neighbor is. You don’t know their background.”

From Border Patrol data Diamant uncovered, we do know over just the last three years, agents have captured more than a half-million people from countries other than Mexico along our southern border, including a growing number of special interest aliens, or SIAs, from terrorist nations like Afghanistan, Iraq, Iran, Sudan, Somalia, Pakistan and Yemen.

“Terrorists can exploit, and their supporters can exploit, a porous border,” Texas Department of Public Safety Director Steven McCraw told Diamant in Austin, Texas.

McCraw is now managing a staggering $800 million the Texas Legislature set aside to seal gaps.

“As long as the border is insecure, it’s going to be a vulnerability. That’s the bottom line,” McCraw Said.

“Deep down in my heart, I would say that something has gone through that has those kind of intentions,” Manjarrez said. “Any of this infrastructure can be exploited by anyone.”

The federal government says almost nothing about known or suspected terrorists caught on the border.

Still, some cases make headlines, like Adnan Shukrijumah, who Judicial Watch’s Chris Farrell described as Al Qaeda’s director of North American operations.

“He had freedom of movement to do essentially what he pleased,” Farrell told Diamant.

Farrell said his sources linked Shukrijumah to an El Paso narco-terrorism ring.

In 2010, the feds indicted Shukrijumah on terror charges for an alleged plot to bomb the New York City subway system.

Shukrijumah spent years on the FBI’s Most Wanted List. It’s believed he entered the United States by air.

The Mexican border is just a couple miles from an airfield that sits inside a private airport community in New Mexico.

Farrell believes Shukrajumah flew in to meet with fellow conspirators in 2010 and 2014. Channel 2 Action News has already confirmed Shukrijumah spent time in Atlanta in 2001.

“He would not show up in Atlanta just by chance,” Farrell said. “It raises questions about networks in Atlanta. Who was he in contact with? What is the support structure that helps facilitate not just his movement and his meetings?”

Few details have emerged about Shukrijumah’s movements in and out of the United States. Pakistan’s army killed Shukrijumah in a 2014 raid. But it’s the big picture that’s most troubling for Farrell.

“The fact is that we have no idea who’s in the country. None,” Farrell said.

In Texas, the focus remains squarely on closing gaps.

“I wear the scars of not knowing who’s in the country,” said Texas State Senator Brian Birdwell.

On Sept. 1, 2001, Flight 77 crashed into the Pentagon just yards from Birdwell’s office.

“Are we going to bat a thousand? No, we’re not. But you got to be at the plate to at least bat,” Birdwell said.